This study is part of a program project the overall goal of which is to determine how insulin resistance alters insulin-stimulated phosphorylation events in vivo in humans and to determine how exercise interacts with insulin to influence these early phosphorylation events. This study will determine if a prior bout of exercise enhances subsequent insulin stimulation of protein phosphorylation by comparing and contrasting five groups: nondiabetic subjects, patients with impaired glucose tolerance, normal glucose tolerant subjects who have a parent with NIDDM, subjects with a history of gestational DM, and subjects with NIDDM.